1. Field of the Invention
The present invention relates to magnification viewers worn by surgeons and dentists. In particular, the invention relates to an assembly for optical viewers or loupes which allow a user to adjust an objective lens at a predetermined distance from an eyepiece lens to vary the focal point.
2. Description of the Related Art
Magnification viewers generally including pairs of magnification loupes, are worn by dentists and surgeons for extended periods of time during clinical procedures, so as to provide clarity of view while avoiding a hunched-over position that can result in debilitating neck and back strain, which can have an adverse effect on the success of the operation. The viewers permit the clinician to operate at a greater working distance from the patient. Higher magnification viewers also reduce the clinician's exposure to aerosols. Because clinicians use magnification viewers during surgery and other procedures requiring manual precision, it is important that they be light-weight, comfortable and have good clarity and wide field of vision while providing high magnification and good depth of field.
Surgical telescopes may be attached to a spectacle frame in one of two manners: outside-the-carrier or prescription lens ("outside-the-lens"), on an adjustment mechanism that provides for adjustment of the interpupillary distance and convergent angle variability, or through-the-lens, permanently cemented and fixed in place. As noted above, magnification viewers used by surgeons and dentists typically have a predetermined magnification. Neither the working distance nor the magnification may be changed without a tedious process of replacing either individual lens elements or the entire optical loupes themselves. Accordingly, there is a need for a simple method for changing the magnification of viewers being worn by a surgeon or dentist, as well as for altering the working distance of viewers having a particular magnification.